The invention relates to a device for separating liquids such as condensate, from gas under pressures such as compressed air, and more specifically to a condensate trap, which is adapted to be connected with a duct so that such gas may flow from one section of the duct, through the device and then back into a further section of the duct, and comprises a liquid trapping housing with a discharge port leading out of the interior of the housing into the surroundings, a valve for covering over and uncovering the port for the discharge of liquid trapped in the housing into the surroundings, such valve comprising a valve member that is able to be moved between a first switching position in which it shuts off the port and a second switching position in which it clears the port and thus puts the interior of the housing in communication with the surroundings, a float which is arranged in the interior of the housing so that it is able to be moved upwards and downwards to a greater or lesser extent in accordance with the amount of liquid in the housing, and is connected with the valve member at least part of whose surface completely shuts off the discharge port in a lowered position of the float and opens the port when the float is in lifted, floating positions.
Such a device or trap, which is used to clear entrained liquids such as condensed water from compressed gas, and more especially from compressed air, has been proposed in the German gebrauchsmuster patent No. 7,036,144, in which case the valve is mounted externally at the bottom of the liquid trapping housing and there is a valve chamber associated with the discharge port. The valve member is placed in the chamber. In its first switching position the valve member is urged by a spring against a valve seat so that the discharge port is shut off. Furthermore the valve member is mechanically linked with a drive piston, whose one piston surface is supplied with driving pressure via a duct. This drive duct leads into the interior of the liquid trapping housing and to a pilot valve, which is shut in the resting, inactive position of the float and is opened in a certain floating position of the float. In the event of the level of the trapped liquid reaching a given height in the interior of the liquid trapping housing, the pilot valve will open and the drive piston will be acted upon by the pressure effective in the interior of the housing so that it is shifted against the force of the return spring and this leads to upward motion of the valve member clear of its seat so that the discharge port is opened. Because some of the liquid is now able to leave the housing, its level therein will be lowered so that the float moves downwards and this in turn leads to closing of the pilot valve and the shutting of the discharge port again.
This known device is made up of a large number of components and has to be generally complex in structure and design in order to ensure proper operation. As a result the device is very expensive to manufacture and highly prone to get out of order when in operation. To take an example, the pilot duct is very liable to foul up so that the operation of the valve member is impaired.